Overspeed brake for elevator cage



May 10, 1966 o. E. MOYER OVERSPEED BRAKE FOR ELEVATOR CAGE 5Sheets-Sheet 2 Filed July 7, 1964 ATTOQNEVS 0. E. MOYER OVERSPEED BRAKEFOR ELEVATOR GAGE May 10, 1966 5 Sheets-Sheet 5 Filed July 7, 1964 wvmwww .R WM an M fiw lmv M 5 08 May 10, 1966 MOYER 3,250,348

' OVERSPEED BRAKE FOR ELEVATOR CAGE Filed July '7, 1964 5 Sheets-Sheet4- A TTOPNEVS May 10, 1966 o. E. MOYER OVERSPEED BRAKE FOR ELEVATOR CAGE5 Sheets-Sheet 5 Filed July 7, 1964 /A/VENT01Q ATTORNEYS.

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United States Patent 3,250,348 OVERSPEED BRAKE FOR ELEVATOR CAGE OscarE. Moyer, Zelienople, Pa., assignor to Universal ManufacturingCorporation, Zclienople, Pa., a corporation of Pennsylvania Filed July7, 1964, Ser. No. 380,763 4 Claims. (Cl. 188-188) This invention relatesto elevators, and more particularly to brakes for automatically stoppingelevators in case they start to fall or otherwise move too fast.

Elevators are often provided with brakes for stopping them automaticallyin emergencies, but such brakes generally operate only in case the cablethat supports the elevator breaks, which would allow the elevator tofall. There are occasions, however, where it may be desirable to stop anelevator because it has started to move too fast and may get out ofcontrol. This is especially true of material handling elevators used atbuilding sites, which are operated by a man at a winch onthe ground. Ifhe misjudges'the speed of the elevator or otherwise lets the elevatorrun away, it may strike the ground before he can stop it. One way ofsolving the problem is disclosed in my patent 2,945,561. The overspeedbrake disclosed therein performs its function satisfactorily, but it ismore complicated and expensive than generally desired, and it is ratherdifiicult to attach to existing elevator installations.

It is among the objects of this invention to provide an elevator brake,which will automatically stop the elevator if it starts to exceed apredetermined speed even if the supporting cable has not broken, whichis relatively simple and inexpensive in construction, and which caneasily be attached to an existing elevator cage in the field.

In accordance with this invention a brake housing is provided that canbe attached to an elevator cage that travels between vertical guiderails. Rollers are carried by the housing for rolling along the rails.Movable means in the housing urge brake shoes toward rail-engagingposition, but a trigger also mounted in the housing normally holds themovable means in shoe-retracted posi- A rotatable governor member ismounted in the housing adjacent the trigger and is driven by therollers. Whenever the rollers reach a predetermined maximum speed anormally retracted trigger releaser, which is movably connected to therotatable governor member, is moved outwardly by centrifugal force farenough to strike the trigger in order to release it from the movablemeans so that the latter can move the shoes to railengaging position.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which FIG. 1 is a front view of an elevatorsuspended in the lower end of a tower;

FIG. 2 is a fragmentary side view of the elevator and tower;

FIG. 3 is an enlarged horizontal section of the brake, with portionsbroken away;

FIG. 4 is a front view of the brake shown in FIG. 3;

FIG. 5 is an enlarged end view of the brake at the end opposite to theone shown in FIG. 2; and

FIGS. 6, 7 and 8 are enlarged vertical sections of the brake taken onthe lines VIVI, VIIVII and VIII- VHI, respectively, of FIG. 4.

Referring to FIGS. 1 and 2 of the drawings, an elevator cage 1, such asused for carrying building materials at a construction site, may besuspended in a portable tower 2 by one or more cables 3 connected by ahitch 4 at the center of the top of the cage. The cable extends up oversheaves (not show) at the top of the tower and then down to a winch onthe ground beside the 3,250,348 Patented May 10, 1966 'ice tower. Anoperator, standing beside the winch, controls the ascent and descent ofthe elevator cage in the tower. The cage is guided by vertical rails 5rigidly secured to the inside of the tower centrally of two oppositesides.

A rectangular frame or brake housing 8 is provided, the length of whichcorresponds to the width of the elevator cage. Secured to the end wallsof the housing are upwardly projecting face plates 9 that are bolted tothe opposite sides of the lower part of the cage in positions to suspendthe housing directly beneath the floor of the cage. Also, as shown inFIGS. 2 and 5, at each end of the housing a pair of grooved rollers 10and 11 engages opposite sides of the adjoining guide rail 5 in order torotate as the cage is raised and lowered. As shown in FIGS. 3 and 4,axially aligned rollers 10 are rigidly mounted on the opposite ends of ashaft 12 that is journaled in bearings 13 secured to the ends of thehousing and also in bearings 14 secured to a pair of spaced verticalplates 15 rigidly mounted in the central portion ofthe housing.

The other pair of rollers is rigidly mounted on the opposite ends of ashaft 18 (FIG. 3) parallel to the first shaft. This second shaft extendsthrough enlarged openings 19 (FIG. 5) in the ends of the housing and isjournaled in bearings 20 mounted on upright brackets 21, the lower endsof which are pivotally connected by bolts 22 to cross bars 23 in thebottom of the housing as shown in FIG. 6. Shaft 18 is urged toward theother shaft by means of coil springs 25, each of which is compressedbetween the upper end of one of the brackets and a horizontal bar 26 atone side of the housing. The central portion of the shaft likewise isjournaled in bearings 27 mounted on the upper ends of small plates 28that are pivoted by bolts 29 to cross bars 30 in the bottom of thehousing near the central plates 15 as shown in FIG. 7. Rollers 11 arepressed against the guide rails 5 by springs 25 and thereby hold theother pair of rollers against the rails also. The two shafts are gearedtogether by a pair of gears 31 rigidly mounted on them so that all ofthe rollers and both shafts must turn in unison at all times while thecage is in motion, even if the rollers on either shaft happened to slipon the rails.

Secured to the outside of each end of the housing above roller 10 is astationary brake shoe 33 (FIGS 2 and 5) having a concave surface thatslides along the adjacent side of one of the guide rails. Opposing eachof these shoes on the opposite side of the adjoining rail is a movablebarke shoe 34, also provided with a concave rail-receiving surface atits inner end. The outer ends of the two movable shoes are mounted onthe opposite ends of movable means, by which they are urged towardrail-engaging position. This movable means includes a pivotally mountedframe which preferably is T-shape and formed from a shaft 35 (FIGS. 3and 4) and a central arm 36 (FIG. 8) projecting radially from it betweenvertical plates 15. The opposite ends of this frame shaft are journaledin bearings 38 secured to the opposite ends of the housing, while thecentral portion of the shaft extends through a pair of bearings 39mounted on the central vertical plates. The movable brake shoes arerigidly mounted on the projecting ends of the shaft. The arm 36 may beformed from a pair of spaced parallel bars 40 welded at one end to asleeve 41 keyed on shaft 35, and connected at their opposite ends by acroses bar 42. The central portions of the side bars have between theman inverted U-shape bracket 43 that is pivotally connected to the barsby bolts 44. The lower surface of the top of this bracket is engaged bythe upper end of a coil spring 45, the lower end of which is seated onanother U-shape bracket 46 pivotally supported by central plates 15. Thespring urges the arm upwardly into the upper of two positions, in whichthe inner ends of the movable brake shoes are swung upward into tightengagement with the adjoining guide rails.

Since the brakes are to be applied to the rails only in emergencies,which it is hoped will never arise, they are normally held retracted bymeans of a trigger 48 that maintains the frame arm 36 in its lowerposition shown in FIG. 8, with the brake shoes released. Preferably,this trigger is formed from a U-shape member 49 pivotally suspended froma horizontal pin 50, the ends of which are mounted in brackets 51 weldedto the central vertical plates. The central portion of the U-shapemember carries a plate 52 that engages the top of cross bar 42 at theouter end of arm 36 in order to hold the arm depressed against theresistance of spring 45. The trigger normally is held in this operativeposition by means of a small coil spring 53 compressed between it and aside bar 54 of the brake housing. As long as the trigger holds the armdepressed, the pivoted brake shoes are free of the guide rails.

If the cage begins to descend faster than a predetermined speedconsidered to be safe, trigger 48 will be released from arm 36,whereupon coil spring 45 will raise the arm and apply the brakes. Torelease the trigger under such an overspeed condition, a governor isprovided that is operated by the rollers. Another feature of thisinvention is that the governor includes a rotatable member or governordisc 56 rigidly mounted on the center of roller shaft 12 beneath thetrigger and the outer end of the arm, as shown in FIGS. 4 and 8. Thisdis-c carries a normally retracted trigger releaser which, when therollers reach a predetermined maximum speed, is moved outwardly bycentrifugal force far enough to strike the trigger to release it fromthe arm. The trigger releaser includes at least one lever 57 that ispivotally connected to one side of the disc on a pin 58 and thatnormally is held in a retracted position against a stop 59 by means of acoil spring 60 connecting it to an adjusting screw 61 attached to a lug62 on the disc. Preferably, the outer end of the lever is made heavy bywelding weights 63 to its opposite sides. In the retraction position ofthe lever the disc can rotate without the outer end of the leverengaging the lower end of the trigger, which extends across the disc.However, as the speed of the disc increases, a point can be reachedwhere centrifugal force will overcome the resistance of spring 60 andswing the outer end of the lever outward beyond the edge of the disc farenough for it to strike the bottom of the trigger and knock it away witharm 36 so that trigger plate 52 will be withdrawn from the arm to allowthe arm to be pushed upward by the spring beneath it. The rotationalspeed of disc 56 that must be reached before the trigger will bereleased can be controlled by adjusting the tension on spring 60.

To reduce by one-half the distance that the governor discs 56 has toturn before the trigger will be struck by the trigger releaser, it ispreferred to provide the disc with a second lever 65 pivotally connectedto the disc on a pin 66 diametrically opposite to pivot pin 58. The twolevers extend in opposite directions from the two pins. To make certainthat lever 65 will swing outward at exactly the same time as the otherlever, it is not re strained by a separate spring but is connected tolever 57 by a link 67 that is pivoted to both of them. One end of thelink is attached to lever 65 between its outer end and and its pivotedinner end, but the opposite end of the link is connected to an inner endportion of the other lever that extends beyond pivot pin 58.

As a further precaution against failure of the governer to operate, andalso to help balance it, it is desirable that another pair of identicallevers be mounted in the same way on the opposite side of the disc.However, the second pair are reversed relative to the first pair. Thatis, the connecting link 67 for one pair of levers is at one side of theshaft 12, while the corresponding link for the other pair of levers isat the opposite side of the shaft. This means that each long lever willbe directly opposite the short lever on the other side of the disc.

During ordinary use of the elevator, the rollers run up and down theguide rails without operating the governor fast enough to cause it torelease the trigger from the spring-pressed arm 36. If for any reasonthe elevator cage starts to descend faster than the safe speed for whichthe governor is set, the levers on the governor disc will swing out andknock the trigger away from the arm. Immediately, the arm will ,be swungupward by spring 45 and that will rotate the shaft 35 on which the brakeshoes are mounted, so the inner ends of the shoes will be swung uptightly against the rails. No matter how much pressure is exerted by thepivoted shoes, the guide rails will not bend because they are backed upby the stationary guide shoes 33 on the opposite side.

In order to release the brakes after they have been applied, a lever 70,shown in FIG. 2, that is rigidly connected to one end of brake shaft 35and that is swung downward when the brakes are applied, is raisedmanually to turn the shaft and thereby swing arm 36 downward until thetrigger snaps into place over its outer end to hold the arm depressed.The braking mechanism then is ready for operation again in case the cagetravels too fast. Lever 70 may be operated by extending its outer endand through a stirrup 71,the upper end of which is pivotally connectedto a longer horizontal lever 72 that in turn is pivotally connected atthe same end to a bracket 73 on the bottom part of the elevator cage.When the free end of this upper lever, which lies on the cage floor, israised it will lift the stirrup and thereby swing the lower lever 70upwardly. On the other hand, when the upper lever is down in itsinactive position, the lower lever is free to swing downward in thestirrup in case shaft 35 turns to apply the brakes.

It will be seen that this brake will do everything that the one coveredby my earlier patent accomplished, but the new one is less expensive andhas the great advantage that it can be sold as a unit for quickattachment to elevator cages already in use.

I claim:

1. An overspeed brake for an elevator cage travelling between verticalguide rails, the brake comprising a housing adapted to be fastened tosuch a cage, rollers carried by the housing for rolling along the guiderails, brake shoes, movable means in the housing urging the shoes towardrail-engaging position, said means including a pivotally mounted frameextending across said housing and having a radially projecting arm, aspring connected with the arm and urging it in one direction, a triggermovably mounted in the housing and engageable with said arm to arrestits movement in said direction for normally holding said frame inshoe-retracted position, a rotatable governor member mounted in thehousing adjacent said trigger and driven by said rollers, and a normallyretracted trigger releaser movably connected to the rotatable member andadapted when the rollers reach a predetermined maximum speed to be movedoutwardly by centrifugal force far enough to strike the trigger torelease it from said arm, whereupon said frame can move the shoes torail-engaging position.

2. An overspeed brake according to claim 1, in which said frame isT-shape and includes a shaft pivotally mounted in the housing andsupporting the brake shoes on its ends, and said arm projects radiallyfrom the center of the shaft.

3. An overspeed brake according to claim 2, including a lever rigidlyconnected at one end to said frame shaft and projecting laterallytherefrom in a direction to swing downward when the brake shoes areapplied, and means for manually lifting the other end of the lever torotate said shaft in a direction to release the brake shoes.

4. An overspeed brake for an elevator cage travelling between verticalguide rails, the brake comprising a housing adapted to be fastened tosuch a cage, rollers carried by the housing for rolling along the guiderails, there being a pair of said rollers engaging opposite sides ofeach rail, means gearing the rollers in each pair together, brake shoes,movable means in the housing urging the shoes toward railengagingposition, a trigger movably mounted in the housing and normally holdingsaid means in shoeretracted position, a rotatable governor disc mountedin the housing adjacent said trigger and driven by said rollers, a pairof levers, means pivotally supporting said levers on said disc ondiametrically opposite sides of its center, said levers being longenough to extend beyond the outer edge of the disc and strike thetrigger, and resilient means 1 normally holding the outer ends of thelevers retracted References Cited by the Examiner UNITED STATES PATENTS1,165,583 12/1915 Farmer 188-188 1,298,066 3/ 1919 Lindquist 187--891,995,274 4/1933 Dunlop 188-188 2,244,893 6/1941 Panter 188l88 2,931,4664/ 1960 Allenbaugh 188l8 8 DUANE A. REGER, Primary Examiner.

4. AN OVERSPEED BRAKE FOR AN ELEVATOR CAGE TRAVELLING BETWEEN VERTICALGUIDE RAILS, THE BRAKE COMPRISING A HOUSING ADAPTED TO BE FASTENED TOSUCH A CAGE ROLLERS CARRIED BY THE HOUSING FOR ROLLING ALONG GUIDERAILS, THERE BEING A PAIR OF SAID ROLLERS ENGAGING OPPOSITE SIDES OFEACH RAIL, MEANS GEARING THE ROLLERS IN EACH PAIR TOGETHER, BRAKE SHOES,MOVABLE MEANS IN THE HOUSING URGING THE SHOES TOWARD RAIL-ENGAGINGPOSITION, A TRIGER MOVABLY MOUNTED IN THE HOUSING AND NORMALLY OFHOLDING SAID MEANS IN SHOERETRACTED POSITION, A ROTATABLY GOVERNOR DISCMOUNTED IN THE HOUSING ADJACENT SAID TRIGGER AND DRIVEN BY SAID ROLLERS,A PAIR OF LEVERS, MEANS PIVOTALLY SUPPORTING SAID LEVERS ON SAID DISC ONDIAMETRICALLY OPPPOSITE SIDES OF ITS CENTER, SAID LEVERS BEING LONGENOUGH TO EXTEND BEYOND THE OUTER EDGE OF THE DISC AND STRIKE THETRIGGER, AND RESILIENT MEANS NORMALLY HOLDING THE OUTER ENDS OF THELEVERS RETRACTED BUT ADAPTED TO PERMIT THEM TO SWING OUTWARDLY BYCENTRIFUGAL FORCE TO RELEASE THE TRIGGER FROM SAID MOVABLE MEANS IF THEROLLERS ATTAIN A PREDETERMINED MAXIMUM SPEED, WHEREUPON SAID MOVABLEMEANS CAN MOVE THE SHOES TO RAIL-ENGAGING POSITION.